Summary
The value of water can be estimated in terms of oppertunity cost, replacement and mitigatory costs and willingness to pay by individuals.
opportunity cost: e.g. the cost to society of forestry using the marginal
quantity of water rather than some other economic activity;
replacement and mitigatory costs: e.g. the cost of having to develop
alternative water sources where forests reduce supply; the reduced cost to
society where forests regulate run-off and hence lower flood risks and the
need for flood prevention; etc.
willingness-to-pay (WTP) by individuals in terms of use and non-use values
for marginal increases in security of supply, enhanced water quality,
reductions in interruptions to supply, etc. from changes in water supply and
quality due to forests.
